1.2.5.1 Background
 Commercial aviation operations are often constrained by poor visibility due to weather conditions. Modern sensors, however, make it possible to accurately detect the position and orientation of a sufficient number of relevant aircraft for ATC system planners to contemplate new "electronic" flight rules. Under these rules flight operations could safely continue despite instrument meteorological conditions that would otherwise shut down or restrict safe aircraft operation. These new sensors, such as ground radar or infrared vision systems, provide spatial data that must be processed by information systems to schedule and space individual aircraft. But results of the scheduling and spacing algorithms need to be monitored by human operators who ultimately have responsibility for safe operation of the air transportation system. This need is particularly salient for air traffic control tower operation which may become highly restricted during low visibility conditions, but corresponding needs for cockpit operation in modern commercial aircraft with restricted visibility also exist.
1.2.5.2 Objectives
The goal of this sub-element is to determine new psychophysical knowledge and devise new wide field of regard (FOR), i.e. > 180 degrees, visual display technology that will allow perceptually accurate, presentation of spatially conformal aircraft position information so that VFR-like operations can be extended into low visibility conditions and to condition in which line of sight contact with aircraft is blocked by obstructions. This knowledge will enable the design of virtual objects displays that will allow operators accurately to see aircraft through fog and physical obstructions. Thus, the fog and obstructions will be made to appear transparent but the range and direction of the aircraft of interest will be accurately displayed.
1.2.5.3 Approach
Initially, a functional testbed for presenting spatially conformal, virtual image information in an unlimited field of regard will be constructed. It will be used for psychophysical testing of the speed and accuracy with which direction and distance information may be presented via virtual objects made to appear visible though fog and physical obstruction. The psychophysical and oculomotor parameters of the displayed virtual objects will be investigated to determine those settings that allow most accurate spatial perception with acceptable visual fatigue.
1.2.5.4 Level 3 Milestones
- FY98a-Testbed for wide field of regard (FOR) presentation of virtual objects
- FY98b-Psychophysical optimization of view parameters for depth presentation w/ wide FOR
- FY99a-Empirical model for accurate depth-direction perception in conditions of transparency
- FY99b-Analysis of depth-cue integration under conditions of transparency
- FY00-Extension depth-cue integration model to nearby virtual objects
- FY01-Extension of depth-direction model to unlimited FOR situations
- FY02-Study of individual differences in depth-direction perception while using wide FOR virtual object displays.
- FY03-Guidelines and evaluation tools for wide FOR displays to ensure accurate depth and direction perception during aircraft and tower operation
1.2.5.5 Monthly Reports
NOVEMBER 1997
A head-mounted display testbed device has been custom-designed by Virtual Research and Virtual Vision to present a fully adjustable stereo display with variable binocular overlap, inter pupilary distance adjustment and focus. Software integration and hardware calibration of this new electronic haploscope is proceding. The SGI Onyx display computer which will be used with this system has been upgraded to System 6.2 and the resulting disturbances to graphics and position sensor timing are being currently assesed. The previously measured very low system latency seems achieveable, but the update rate is no longer constant, threatening to serious degrade the predictive tracking we wish to introduce.
JUNE 1998 (cumulative progress):
The systems problem preventing low latency image rendering with IRIX 6.2 has been solved by introduction of a patch provided by SGI after considerable encouragement. Performance equivalent to that previously obtained with IRIX 5.3 was achieved in March.
A tower simulation displayed via the custom stereo head mounted display has been completed for use with the head mounted display that can allow users to visualize approaching and departing aircraft as if they were actually located at a control tower either at SFO (San Francisco) of KATL (Atlanta). This simulation allows the demonstration of perceptual instability and distance estimation errors that could obtain in a fielded head mounted display for use within a tower. Aircraft shapes are corrected rendered and presented with data tags; the airport map is presented only as a scanned chart mapped onto the ground plane as a texture. Calibration for presentation of distant and near targets is currently being obtained via improved understanding of the World Took Kit functions needed. These were poorly documented with respect to mathematical details. The current system could be connected to aircraft traffic data on the WEB via sockets and can be used to study the role of the parameters of binocular presentation to the apparent transparency of the nearby physical environment when the distant aircraft are presented against it via the see-through display. A study of the role that latency plays in disturbing accurate depth localization of virtual objects, such as are used for the control tower simulation, has been completed and will be reported at the next meeting of the Human Factors and Ergonomics Society in October. In general the hardware and software elements of the testbed planned for the first year of this project have been completed. Explicit experimental work with the tower simulation will proceed next year and signal processing work on the head position signals will also be conducted to aid image stabilization.
Models for predictive tracking have been produced via MATLAB and then converted to C code suitable for realtime use by the C code compilers within MATLAB. New architectures for the introduction of predictive tracking for presentation of the virtual objects(aircraft) in the head mounted display.
JULY 1998:
PROGRESS AND PUBLICATIONS:
Optical and electronic alignment of the head mounted display has revealed an approximate 10 degree lateral shift not previously noticed. Investigations are progressing to identify the source of this to avoid having to use a software correction which will sacrifice some field of view. Consequently, completion of the 98b milestone may be delayed until August or September.
The distortion field in the virtual environment room is being remeasured for improved spatial calibration and spatialized sound has been added to the basic simulation software capacity. This addition will be demonstrated next month.
Three psychophysical functions of the detectability of variation in rendering latency of veritual objects have been completed. These may be the first such functions ever recorded and will help understand the relationship between the minimum noticeable latency and its effect on the percieved depth of a virtual objects depicted at great distance, i.e. > 0.5 km.
PUBLICATION ACTIVITY:
- Begault, Durand R. Ellis, Stephen R. , and Wenzel, Elizabeth M. (1998) Headphone and head-mounted visual displays for virtual environments, 15th International Conference Of The Audio Engineering Society, submitted paper
- Ellis, Stephen R. & Menges, Brian M. (1998) Operator Localization of Virtual Objects, Proceedings of MMM '98, Z¸rich, Switzerland, invited paper.
SIGNIFICANT EXTERNAL LIAISONS:
Work continues on the establishment of a Nonreimbursed Space Act Agreement between NASA Ames and a local research laboratory for the study of the impact of latency on operator behavior in virtual environments. Currently, the agreement is being reviewed by NASA lawyers.
ISSUES:
None.
AUGUST 1998:
PROGRESS AND PUBLICATIONS:
The haploscope is being brought to Virtual Research for realignment. Virtual research has assembled several possible new backlights with diffusing material provided by Ames and has developed a configuration that will double the display luminance. It will be installed into the haploscope during realignment.
The distortion field in the virtual environment room has being remeasured for improved spatial calibration and the new larger distortion field has been visualized in MATLAB
Psychophysical functions have been measured with improved blocking techniques. The false alarm rate appears to be constant but longer blocking will be investigated to determine if this remains true under generalized conditions. Sensitivity to changes in rendering latency during head and body movement has been tested in addition to that during hand movement. Initial estimates show sensitivity during head/body movement is about half of that during hand movement, but dprines have not yet been stably estimated.
PUBLICATION ACTIVITY:
None.
SIGNIFICANT EXTERNAL LIAISONS:
Work continues on the establishment of a Nonreimbursed Space Act Agreement between NASA Ames and a local research laboratory for the study of the impact of latency on operator behavior in virtual environments. Currently, the agreement is being reviewed by NASA lawyers. Extensions to include studies of motion sickness in collaboration with Pat Cowings laboratory in SL have begun.
ISSUES:
None.
SEPTEMBER-OCTOBER 1998:
PROGRESS AND PUBLICATIONS:
The ATC Tower simulation is being rewritten to accept CTAS-like data records for ultimate connection to live air traffic data. The expanded spatial calibration data have been verified by remeasurement after implementation of the distortion correction. Generally, the system provides sub centimeter accuracy, with the largest errors associated with the less frequently used extreme positions near the walls.
PUBLICATION ACTIVITY:
- Ellis,, S.R., Adelstein, B.D. , Baumeler,S ., Jense, G.J., & Jacoby, R.H. Sensor Spatial Distortion, Visual Latency, And Update Rate Effects On 3d Tracking In Virtual Environments (has been accepted for presentation at the 1999 IEEE VRAIS conference in Houston, Texas, next March)
- Begault, Durand R. Ellis, Stephen R. , and Wenzel, Elizabeth M. (1998) Headphone and head-mounted visual displays for virtual environments, 15th International Conference Of The Audio Engineering Society, published.
SIGNIFICANT EXTERNAL LIAISONS:
The Nonreimbursed Space Act Agreement between NASA Ames and a local research laboratory for the study of the impact of latency on operator behavior in virtual environments has been signed off at the Branch and Division level.
ISSUES:
None.
NOVEMBER 1998:
PROGRESS AND PUBLICATIONS:
Programming continues on the adaptation of the Tower Simulation to accepting trajectory input from CTAS files and data sources. The structure of the simulation is being adapted to distributed computation so as to allow parallelism which will improve dynamic performance during high frequency sampling from a socket port.
SIGNIFICANT EXTERNAL LIAISONS:
An SBIR Phase I contract has been approved with a consortium organized by Seagull Technologies, to study the performance requirements for an ATC tower traffic display of the type addressed by this subelement. Consultants from Hughes Electronics, USC, and UNC will be involved with this project. The original solicitation for the SBIR was begun independently of this subelement but because of the close technical relationship, the SBIR contract work will be coordinated with this subelement.
ISSUES:
None.
DECMBER 1998 - JANUARY 1999:
PROGRESS AND PUBLICATIONS:
A new Tower Simulation smoothly displaying aircraft trajectories from episodic, time- stamped data has be completed and runs well. It should be possible to run it at 30hz with 60 aircraft and at around 60hz with 30 aircraft. There were several meetings with the Task Requester to assess the quality of the calibration of the adjusted see-through helmet. The stereo parameters were modified. The company who designed our API is currently being contacted regarding several issues involving aspects of the API that do not appear to work as expected. Discussions have been held about the integration of the predictive filter driver and the modification of AST to use the new calibration tables and the filter driver seamlessly. The predictive filter has been optimized to closely track measured position and remove most of the positional noise introduced by initial implementations. Pilot testing indicated that ad two step prediction of 33 msec provides correction for the system rendering delay with apparently subthreshold prediction artifact. An experiment is being designed to verify this observation. Latency discrimination experiments have been completed with six subjects confirming initial observations that base reference latencies between 27 and 193 msec have no effect on latency discrimination. Weber's Law appears violated for this judgment.
SIGNIFICANT EXTERNAL LIAISONS:
The SBIR Phase I contract is underway with a consortium organized by Seagull Technologies, and visits to local ATC facilities are being planned.
ISSUES:
None. |
